Noob Question

I downloaded ati tools today and I like it, but it's pretty obvious that I have no idea what I'm doing, so I'm coming here for help.

I've no desire to overclock my comp, it has enough trouble at normals speeds, so all I wanted to do was check temps and things like that because my computer has had overheating problems in the past. I have a Radeon 9800 pro. Here are my questions:

If I scan for artifacts, after about three minutes my computer starts beeping at me and I get yellow lines all across the the 3D view. This is bad, obviously, but what does in mean?

Second, if I try to test max core, it just crashes. This is also bad. What does it mean?